Integrating or averaging pitot tubes are eminently suitable for measuring exhaust and flue gases . They are resistant to dirt and condensates. The choice of materials for measuring probes to monitor the combustion of chemical residues is often a difficult one. As soon as the exhaust gas falls below dew point, halogens may turn surprisingly acidic. For example, a mixture of sulphuric acid, hydrochloric acid and hydrofluoric acid will soon corrode most metals and make any subsequent measurements impossible.
Only very few metal alloys can be safely used under these conditions. The problem is as follows: the material price of these alloys hardly differs from that of precious metals and processing them to obtain probe components is often extremely time-consuming and expensive.
The cost-effective solution developed by System Controls for such complex special applications makes use of synthetic dynamic pressure probes. This company, which specialises in flow meters, manufactures teflon probes with reduced surface resistance for use under extremely corrosive conditions. These probes are particularly corrosion-resistant. By doping the material with carbon, static charging – which could have fatal consequences in explosive atmospheres – can be safely avoided.